Researchers from Hong Kong Baptist University have described a new box jellyfish, Tripedalia maipoensis, from the brackish gei wais of Mai Po Nature Reserve. Averaging about 1.5 cm in body length, the species has 24 eyes arranged in four rhopalia—two lens eyes and four light-sensitive receptors per rhopalium—giving near–360° vision. First recorded in 2020, the jellyfish is the third species in its genus and the first Tripedalia reported in Chinese waters; broader surveys are needed to map its range.
New 24-Eyed Box Jellyfish Discovered Near Hong Kong — Sees Almost 360°
A Creature With 24 Eyes Can See Everywhere At OnceAbstract Aerial Art - Getty Images
Scientists have described a previously unknown box jellyfish living in brackish shrimp ponds near Hong Kong, revealing another surprising twist in the diversity of Cnidarians.
Published in Zoological Studies, the discovery by researchers at Hong Kong Baptist University (HKBU) documents a new member of the family Tripedaliidae, named Tripedalia maipoensis. Like other members of the class Cubozoa, this species has a cube-shaped bell and is the third species described in the genus Tripedalia and the first recorded in Chinese waters.
The tiny jellyfish—about 1.5 centimeters in body length on average—was first found in 2020 in the gei wais (traditional brackish shrimp ponds) of the Mai Po Nature Reserve and has been observed there in follow-up surveys. Although named for its type locality, the authors note that the gei wais are connected by tidal channels to the Pearl River Estuary, so the species likely occurs in adjacent waters as well.
Extraordinary Eyes, Compact Body
Despite its small size, Tripedalia maipoensis has one of the most remarkable visual systems in the animal kingdom: 24 eyes organized into four sensory organs called rhopalia. Each rhopalium contains six eyes—two lens-bearing eyes capable of forming images and four simpler photoreceptors that detect light and shadow. This arrangement gives the animal near–360-degree visual awareness, a useful adaptation for maneuvering through complex habitats such as mangrove roots and seagrass beds.
“We named the new species Tripedalia maipoensis to reflect its type locality—where the new species was first found,” said Qiu Jianwen, a biologist and co-author from HKBU. “Although it is currently known only in Mai Po, we believe that this species is also distributed in the adjacent waters of the Pearl River Estuary as the gei wais are connected to the estuary through a tidal channel.”
Why This Matters
Box jellyfish vary widely in size and toxicity: for example, the Australian box jellyfish Chironex fleckeri can reach roughly one foot across and is among the most venomous animals known, while many other species are tiny and harmless to people. The discovery of T. maipoensis underscores how much remains undiscovered in coastal ecosystems, even in well-studied regions.
The researchers call for broader coastal surveys along China’s shoreline to map the full distribution of this species and to better understand its ecology and conservation status. Mai Po Nature Reserve, celebrated by the World Wide Fund for Nature as “a paradise for birds and a beautiful, irreplaceable piece of China’s wetland kaleidoscope,” remains an important site for biodiversity research.
This finding highlights how marine life continues to challenge our expectations—tiny, brainless-looking animals can nevertheless possess sophisticated sensory systems that allow them to thrive in complex environments.
